The need for supplying clean air to the air intake of internal combustion engines requires the use of air filters. Where the internal combustion engine is operating in a dust laden environment, air filters become clogged very rapidly and must either be replaced by a new filter or cleaned of the dust which clogs the filter. To shut down an engine in order to replace the dirty filter with a new filter, or to remove and clean the dirty filter and then to replace the cleaned filter takes valuable time during which the machine operated by the engine and the engine operator are unable to perform the function for which they are primarily intended. In order to avoid shutting down the engine, operators often will allow the engine to run with a dirty air filter longer than it should, thereby resulting in inefficient engine use.
If the air filter can be cleaned periodically or continuously while it continues to filter the air supply to the engine, substantial economy can be obtained by reducing the down time of the engine and by reducing the frequency of filter replacement.
The need for means to periodically or continuously clean an air filter while it performs its primary function has long been recognized and many devices have been developed to meet the need. The devices developed have met with varying degrees of commercial success but the fact that there are many internal combustion engines at the present time which operate without a self-cleaning air filter suggests that the need is not being fully met.
It is an object of the present invention to provide an improved self-cleaning air filter which provides for periodic, or continuous back flushing of successive portions of the air filter while the remainder of the air filter which is not being back flushed continues to filter the air supply. Dirt removed by the back flushing operation is discharged from the filter housing without recontamination of the filter or the air being treated by the filter.
It is a further object of the invention to provide a self-cleaning air filter which utilizes commercially available cylindrical air filter cartridges and a cylindrical filter housing having a readily removable cover at one end permitting rapid insertion of the filter cartridge therein and a rapid removal of the filter cartridge therefrom.